Floodlight



C. A. B. HALVORSON, JR. FLOODLIGHT.

APPLICATION FILED DEC.27. 1918. 1,371,761 Patented Mar. 15,-192L.

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UNITED STATES P 1 'l' ENT oFFicE.

CROMWELL A. B. HALVORSON, JR, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

FLOODLIGET.

Specification of Letters Patent. Patented Mar. 15, 1921.

Application filed December 27, 1918. Serial No. 268,557.

Massachusetts, have invented certain new and useful Improvements in Floodlights, of \\'lll(.'l1 the following is a specification.

My invention relates to improvements in flood lights, that is to sa'y,-lighting equipments for distributing the light from a source in certain desired directions, and the object of the invention is to accomplish this result efliciently without the use of an independent reflector as an adjunct to the lighting unit proper. This result I secure by so modifying the ordinary protecting or inclosing globe which is generally used as an essential element of the larger light units, that it will serve as the reflector of the outfit. In conjunction with the globe reflector a refractoimay be used for more eflicient distribution of the light.

In the accompanying drawing my invention is illustrated as follows:

Figure 1 is an elevation of a flood light unit embodyingmy invention; Fig. 2 is a partial vertical section of a modified form of the light unit, but omitting the light source, and Fig. 3 is a. transverse section of the inclosing globe reflector.

In Fig. 1 the canopy or support 10 for the light source and its accessories is indicated as of the usual character, and requires no special description. The light source is here shown as an ordinary incandescent lamp 11, to which the current is conveyed through the binding posts 12, 12, but any other source of light, as, for instance, a suitable arc lamp ma. be used. Surrounding the luminous portion of the lamp is the refractor 13, which as here shown has the shape of a truncated cone, although it may deviate, more or less, from this general form, and it may for some purposes be entirely omitted. As shown in Fig. 2, the refractor is composed of two concentric elements, the inner one, 13', having its outer surface formed with circumferential horizontal prisms, as indicated, and the outer one, 13 having its inner surface formed with longitudinally extending prisms 13. These two elements are slightly spaced apart and suitably fitted together, and the whole structure is supported by the canopy in any convenient manner.

The function of the horizontal prisms on the element 13' is to bend the rays of light which reach the same from the source downwardly, more or less, according to the angularity of the prisms, and the function of the longitudinal prisms on the element 13 is to bend the rays which they receive laterally, more or less, according to the angularity of these prisms;

Surrounding the light source and refractor is the guard or protecting globe 14, which is seated with its upper edge 15, against the canopy and is there held by a suitable catch 16, which may be lifted and the globe released.

This globe, in accordance with my invention, instead of being transparent or translucent all over as heretofore used, has a selected portion of its surface converted into a reflector, whereby all or practically all the light flux from the source is caused to issue from the remaining transparent or translucent portion. In the drawing two forms of globes are shown, the one in Fig. 1 being closed at the bottom, while that shown in Fig. 2 is open at its lower end. The reflecting portion 17 of the globe extends from the top to the bottom and throughout a considerable portion, say 18Q of the circumference, but the invention is not limited to this particular angular extent of reflecting surface.

The reflecting surface is preferably a chemical deposit 18 of silver on the outer surface of the globe. Two ribs 19, 19 are formed on the outer surface on opposite sides of the globe and throughout its length, and

the silvering is preferably extended over these ribs, as shown in Fig. 3, and 1s also extended over the upper edge in both forms of globe and oi er the upper and lower edges in the form shown in Fig. 2. As a protection to the silvering and for the purpose of carrying the heat from the globe a rather heavy layer 20 of closely adherlng copper or other suitable metal is depos ted upon the silver, and this metal deposit 1s also extended over the ribs 19, and over the edge 0} edges of the lobe, so as to be anchored to the globe. T e copper is deposited by the usual electrolytic process.

It is not absolutely necessary that the silvering be carried over the ribs and edges, so as to be anchored to the globe independently of the copper protective deposit, because light rays proceeding from the source in di-' rections toward the transparent (or translucent) part of the globe pass directly into the restricted field of illumination, while the rays from the sourcewhich, after passing the refractor strike the reflecting portion of the globe, are reflected toward the transparent portion of the same and issue into practically the same restricted field of illumination.

If a refractor, such as described, or an equivalent of the same is used, the greater part of the rays from the source are bent downwardly and outwardly before they strike any part of the globe, but otherwise the general effect is the same; that is to'say,

all or practically all the light flux from the source is directed into a desired restricted field of illumination, whether the refractor is or is not used. In a light unitof this general character the incandescent lamp or other light source is the most delicate and fragile element and requires frequent renewal, and

be of ordinaryan'd cheap construction, so

ing from thesurfaceof the globe, slightly undercut depressions or grooves 01', more it is therefore important that this element that if one breaks or is burned out, it ma readily bereplaced by another Withouta fecting the light distribution. My invention secures this'result since the meansfor giving direction and securing the desired distribution of light are not dependent upon any particular construction of the light It is evident that, instead of ribs projectgenerally, corrugations, maybe formed on the globe for anchoring the silver and copper deposits thereon; the marginal walls of the depressions serving in that case as ribs. What I claim asnew and desire to secure by Letters Patent of the United States, is,

A rotecting guard for a lighting unit, composed of a globe of light transmitting material, two substantially diametrically located ribs extendingthroughout the len th of the globe on the outer surface thereo a deposit of silver extending between the two ribs throughout the length of the globe on one side thereof, and a protecting electrolytic deposit of copper over the silvering, the ribs and the edges of the globe. I r Y V In witness whereof, I have hereunto set my hand this 24th day of December, 1918.

CROMWELL A. B. HALVORSON, Jr. 

